Pleural cavity

In human anatomy, the pleural cavity is the body cavity that contains the lungs. The lungs are surrounded by the pleurae, a serous membrane which folds back upon itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural space; it normally contains a small amount of pleural fluid. The outer pleura (parietal pleura) is attached to the chest wall. The inner pleura (visceral pleura) covers the lungs and adjoining structures, i.e. blood vessels, bronchi and nerves.

The parietal pleura is highly sensitive to pain; the visceral pleura is not due to its lack of sensory innervation.

Functions

The pleural cavity, with its associated pleurae, aids optimal functioning of the lungs during respiration. The pleurae are coated with lubricating pleural fluid which allows the pleurae to slide effortlessly against each other during ventilation. Surface tension of the pleural fluid also leads to close apposition of the lung surfaces with the chest wall. This physical relationship allows for optimal inflation of the alveoli during respiration. Movements of the chest wall, particularly during heavy breathing, are coupled to movements of the lungs since the closely opposed chest wall transmits pressures to the visceral pleural surface and, hence, to the lung itself.

Pleural fluid

Pleural fluid is a serous fluid produced by the pleurae. A normal 70 kg human has approximately 12-15 mL of pleural fluid.

In normal pleurae, most fluid is produced by the parietal circulation (intercostal arteries) via bulk flow and reabsorbed by the lymphatic system. Thus, pleural fluid is continuously produced and reabsorbed. The rate of reabsorption may increase up to 40x before significant amounts of fluid accumulate within the pleural space.

In humans, there is no anatomical connection between the left and right pleural cavities, so in cases of pneumothorax, the other hemithorax will still function normally.

Blood supply

In humans, the visceral pleura has a dual blood supply, receiving blood from the bronchial and from the pulmonary arteries.

Development of the pleural cavity

See also

• Pleural disease
• Vertebrate trachea
• Capillaries
• Larynx
• Pharynx
• Epiglottis
• Rings of cartilage
• Bronchus
• Bronchioles
• Thoracic cavity

Additional images

References

External links

• Photo of dissection at kenyon.edu